feat(telemetry): add dashboard panels for new T3 metrics

Visualise the metrics added in this series:
- consensus-health: "Ledger History Mismatch Rate by Reason"
  (xrpld_ledger_history_mismatch_total by reason — fork diagnostics)
- fee-market: "Queue Abandonment Rate (Expired)" and "Queue Admission
  Rejections (Dropped)" (xrpld_txq_expired_total / dropped_total)
- peer-network: "Reduce-Relay Peer Selection" and "Reduce-Relay Missing-Tx
  Frequency" (xrpld_reduce_relay_metrics)
- system-node-health: "Ledger Acquire Duration" and "Ledger Acquire Rate by
  Outcome" (ledger.acquire span)

otel-collector-config.yaml: add outcome and acquire_reason spanmetrics
dimensions so the ledger.acquire outcome breakdown populates.

All panels follow the existing template: $node filter, exported_instance in
legends, Title Case, axis labels.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

docker/telemetry/grafana/dashboards/consensus-health.json

@@ -965,6 +965,45 @@
         },
         "overrides": []
       }
+    },
+    {
+      "title": "Ledger History Mismatch Rate by Reason",
+      "description": "Rate of built-vs-validated ledger mismatches broken down by reason (prior_ledger, close_time, consensus_txset, same_txset_diff_result, different_txset, unknown). Answers WHY the node forked \u2014 Byzantine close-time disagreement vs sync drift vs tx-processing difference.",
+      "type": "timeseries",
+      "gridPos": {
+        "h": 8,
+        "w": 24,
+        "x": 0,
+        "y": 96
+      },
+      "options": {
+        "tooltip": {
+          "mode": "multi",
+          "sort": "desc"
+        }
+      },
+      "targets": [
+        {
+          "datasource": {
+            "type": "prometheus"
+          },
+          "expr": "sum by (reason, exported_instance) (rate(xrpld_ledger_history_mismatch_total{exported_instance=~\"$node\"}[5m]))",
+          "legendFormat": "{{reason}} [{{exported_instance}}]"
+        }
+      ],
+      "fieldConfig": {
+        "defaults": {
+          "unit": "ops",
+          "custom": {
+            "axisLabel": "Mismatches / Sec",
+            "spanNulls": true,
+            "insertNulls": false,
+            "showPoints": "auto",
+            "pointSize": 3
+          }
+        },
+        "overrides": []
+      }
     }
   ],
   "schemaVersion": 39,

docker/telemetry/grafana/dashboards/peer-network.json

@@ -150,6 +150,98 @@
         },
         "overrides": []
       }
+    },
+    {
+      "title": "Reduce-Relay Peer Selection",
+      "description": "Transaction reduce-relay efficiency: peers selected as relay sources vs suppressed, plus peers with the feature disabled. A high suppressed:selected ratio proves reduce-relay is saving bandwidth; a high not_enabled count means stale peers force full relay.",
+      "type": "timeseries",
+      "gridPos": {
+        "h": 8,
+        "w": 12,
+        "x": 0,
+        "y": 16
+      },
+      "options": {
+        "tooltip": {
+          "mode": "multi",
+          "sort": "desc"
+        }
+      },
+      "targets": [
+        {
+          "datasource": {
+            "type": "prometheus"
+          },
+          "expr": "xrpld_reduce_relay_metrics{metric=\"selected_peers\",exported_instance=~\"$node\"}",
+          "legendFormat": "Selected [{{exported_instance}}]"
+        },
+        {
+          "datasource": {
+            "type": "prometheus"
+          },
+          "expr": "xrpld_reduce_relay_metrics{metric=\"suppressed_peers\",exported_instance=~\"$node\"}",
+          "legendFormat": "Suppressed [{{exported_instance}}]"
+        },
+        {
+          "datasource": {
+            "type": "prometheus"
+          },
+          "expr": "xrpld_reduce_relay_metrics{metric=\"not_enabled_peers\",exported_instance=~\"$node\"}",
+          "legendFormat": "Not Enabled [{{exported_instance}}]"
+        }
+      ],
+      "fieldConfig": {
+        "defaults": {
+          "unit": "none",
+          "custom": {
+            "axisLabel": "Peer Count",
+            "spanNulls": true,
+            "insertNulls": false,
+            "showPoints": "auto",
+            "pointSize": 3
+          }
+        },
+        "overrides": []
+      }
+    },
+    {
+      "title": "Reduce-Relay Missing-Tx Frequency",
+      "description": "Frequency of on-demand transaction fetches triggered when a peer is missing a relayed transaction. A rising value means the suppression is too aggressive and the on-demand fetch path is growing.",
+      "type": "timeseries",
+      "gridPos": {
+        "h": 8,
+        "w": 12,
+        "x": 12,
+        "y": 16
+      },
+      "options": {
+        "tooltip": {
+          "mode": "multi",
+          "sort": "desc"
+        }
+      },
+      "targets": [
+        {
+          "datasource": {
+            "type": "prometheus"
+          },
+          "expr": "xrpld_reduce_relay_metrics{metric=\"missing_tx_freq\",exported_instance=~\"$node\"}",
+          "legendFormat": "Missing Tx Freq [{{exported_instance}}]"
+        }
+      ],
+      "fieldConfig": {
+        "defaults": {
+          "unit": "none",
+          "custom": {
+            "axisLabel": "Frequency",
+            "spanNulls": true,
+            "insertNulls": false,
+            "showPoints": "auto",
+            "pointSize": 3
+          }
+        },
+        "overrides": []
+      }
     }
   ],
   "schemaVersion": 39,

docker/telemetry/grafana/dashboards/system-node-health.json

@@ -2051,6 +2051,91 @@
         },
         "overrides": []
       }
+    },
+    {
+      "title": "Ledger Acquire Duration (Inbound Fetch)",
+      "description": "p95/p50 duration of the ledger.acquire span (InboundLedger): how long it takes to fetch a missing ledger from peers. A spike signals the node is falling behind or recovering from a fork. Populated under back-fill / sync activity.",
+      "type": "timeseries",
+      "gridPos": {
+        "h": 8,
+        "w": 12,
+        "x": 0,
+        "y": 126
+      },
+      "options": {
+        "tooltip": {
+          "mode": "multi",
+          "sort": "desc"
+        }
+      },
+      "targets": [
+        {
+          "datasource": {
+            "type": "prometheus"
+          },
+          "expr": "histogram_quantile(0.95, sum by (le, exported_instance) (rate(traces_span_metrics_duration_milliseconds_bucket{exported_instance=~\"$node\", span_name=\"ledger.acquire\"}[5m])))",
+          "legendFormat": "P95 Acquire [{{exported_instance}}]"
+        },
+        {
+          "datasource": {
+            "type": "prometheus"
+          },
+          "expr": "histogram_quantile(0.50, sum by (le, exported_instance) (rate(traces_span_metrics_duration_milliseconds_bucket{exported_instance=~\"$node\", span_name=\"ledger.acquire\"}[5m])))",
+          "legendFormat": "P50 Acquire [{{exported_instance}}]"
+        }
+      ],
+      "fieldConfig": {
+        "defaults": {
+          "unit": "ms",
+          "custom": {
+            "axisLabel": "Duration (ms)",
+            "spanNulls": true,
+            "insertNulls": false,
+            "showPoints": "auto",
+            "pointSize": 3
+          }
+        },
+        "overrides": []
+      }
+    },
+    {
+      "title": "Ledger Acquire Rate by Outcome",
+      "description": "Rate of completed ledger.acquire spans broken down by outcome (complete / failed). A rising failed rate indicates the node cannot fetch needed ledgers from its peers. Requires the outcome spanmetrics dimension.",
+      "type": "timeseries",
+      "gridPos": {
+        "h": 8,
+        "w": 12,
+        "x": 12,
+        "y": 126
+      },
+      "options": {
+        "tooltip": {
+          "mode": "multi",
+          "sort": "desc"
+        }
+      },
+      "targets": [
+        {
+          "datasource": {
+            "type": "prometheus"
+          },
+          "expr": "sum by (outcome, exported_instance) (rate(traces_span_metrics_calls_total{exported_instance=~\"$node\", span_name=\"ledger.acquire\"}[5m]))",
+          "legendFormat": "{{outcome}} [{{exported_instance}}]"
+        }
+      ],
+      "fieldConfig": {
+        "defaults": {
+          "unit": "ops",
+          "custom": {
+            "axisLabel": "Acquisitions / Sec",
+            "spanNulls": true,
+            "insertNulls": false,
+            "showPoints": "auto",
+            "pointSize": 3
+          }
+        },
+        "overrides": []
+      }
     }
   ],
   "schemaVersion": 39,

docker/telemetry/grafana/dashboards/xrpld-fee-market.json

@@ -375,6 +375,84 @@
         },
         "overrides": []
       }
+    },
+    {
+      "title": "Queue Abandonment Rate (Expired)",
+      "description": "Rate of transactions expired out of the queue (LastLedgerSequence passed). Rising expiry means submitters under-bid the escalating fee and gave up \u2014 a demand-frustration signal.",
+      "type": "timeseries",
+      "gridPos": {
+        "h": 8,
+        "w": 12,
+        "x": 0,
+        "y": 32
+      },
+      "options": {
+        "tooltip": {
+          "mode": "multi",
+          "sort": "desc"
+        }
+      },
+      "targets": [
+        {
+          "datasource": {
+            "type": "prometheus"
+          },
+          "expr": "sum by (exported_instance) (rate(xrpld_txq_expired_total{exported_instance=~\"$node\"}[5m]))",
+          "legendFormat": "Expired / Sec [{{exported_instance}}]"
+        }
+      ],
+      "fieldConfig": {
+        "defaults": {
+          "unit": "ops",
+          "custom": {
+            "axisLabel": "Expired / Sec",
+            "spanNulls": true,
+            "insertNulls": false,
+            "showPoints": "auto",
+            "pointSize": 3
+          }
+        },
+        "overrides": []
+      }
+    },
+    {
+      "title": "Queue Admission Rejections (Dropped)",
+      "description": "Rate of transactions refused admission to the queue, by reason. queue_full means the queue is at capacity \u2014 admission-control backpressure distinct from expiry and from job-queue overflow.",
+      "type": "timeseries",
+      "gridPos": {
+        "h": 8,
+        "w": 12,
+        "x": 12,
+        "y": 32
+      },
+      "options": {
+        "tooltip": {
+          "mode": "multi",
+          "sort": "desc"
+        }
+      },
+      "targets": [
+        {
+          "datasource": {
+            "type": "prometheus"
+          },
+          "expr": "sum by (reason, exported_instance) (rate(xrpld_txq_dropped_total{exported_instance=~\"$node\"}[5m]))",
+          "legendFormat": "{{reason}} [{{exported_instance}}]"
+        }
+      ],
+      "fieldConfig": {
+        "defaults": {
+          "unit": "ops",
+          "custom": {
+            "axisLabel": "Dropped / Sec",
+            "spanNulls": true,
+            "insertNulls": false,
+            "showPoints": "auto",
+            "pointSize": 3
+          }
+        },
+        "overrides": []
+      }
     }
   ],
   "schemaVersion": 39,

docker/telemetry/otel-collector-config.yaml

@@ -106,6 +106,9 @@ connectors:
       - name: method
       - name: grpc_role
       - name: grpc_status
+      # ledger.acquire dimensions (bounded: outcome, acquire reason).
+      - name: outcome
+      - name: acquire_reason
 
 exporters:
   debug: